Tile trouble

Hi!
I'm having a little trouble with a game I'm trying to make.... It's a Red Alert style game... But when I mark a tile and the marked tile goes past the screen up or to the left something weird happens... Could somebody plz take a look at my source?

When I run the source the only thing that happens when you click is the tile is surrounded with a green square which is sticky and won't go away.
If it's a RedAlert Game why do you need to select the terrain?

Bug: When you point at the edge of the screen and click it causes a lockup

I know about the bug and that the green square wont go away, but its WERY erly in the prgress and I know how to handle that but when you select a thing and the green square goes out of the screen to the left or to the top something weird happens.... Is there any on that know why that happens?